1. Field of the Invention
The present invention relates to a sheet stacking apparatus and a sheet stacking method which are applicable to a corrugated paperboard box making machine.
2. Description of the Related Art
Heretofore, various proposals have been made regarding a sheet stacking apparatus equipped with a leading-edge regulating member. For example, a hopper apparatus described in the following Patent Document 1 comprises a front contact plate contactable with a flattened corrugated paperboard box conveyed and stacked (transferred) therein. The front contact plate is primarily comprised of a support plate, a plate spring and a protective plate. The plate spring and the protective plate are suspended with play, with respect to an obverse surface of the support plate. A closed or open cell sponge rubber is interposed between the support plate and the plate spring. The plate spring is made of a metal, and configured to have a spring constant equal to that of the sponge rubber, in regard to collision with the flattened corrugated paperboard box. The protective plate is made of a hard resin, such as hard urethane rubber.
In the hopper apparatus described in the Patent Document 1, when a plurality of flattened corrugated paperboard boxes sequentially collide with the front contact plate from an obverse side of the front contact plate, a cyclic load is applied to the plate spring and the protective plate for a long time period. In regard to the cyclic load, the plate spring itself has elasticity, and the sponge rubber is interposed between the support plate and the plate spring. Thus, the front contact plate described in the Patent Document 1 has a significant effect of absorbing an impact force from the flattened corrugated paperboard box.